WO2017010450A1 - Multi-lobe bearing and supercharger - Google Patents

Abstract

Provided is a multi-lobe bearing equipped with: a bearing surface (20a) the shape of which in a cross section perpendicular to the axial direction of a shaft (8) includes a plurality of lobes; and an oil supply groove (20e) which is disposed on the bearing surface, extends in the axial direction of the shaft, and has a bearing clearance (c11) at the front-side end part (20h) in the rotation direction of the shaft, that is smaller than a bearing clearance (c12) at the back-side end part (20i) in the rotation direction.

Description

Multi-arc bearings and turbochargers

This disclosure relates to a multi-arc bearing and a supercharger that support a shaft.

Conventionally, a turbocharger in which a shaft is rotatably supported by a bearing housing is known. A turbine impeller is provided at one end of the shaft, and a compressor impeller is provided at the other end. The supercharger is connected to the engine, and the turbine impeller is rotated by exhaust gas discharged from the engine. The rotation of the turbine impeller causes the compressor impeller to rotate through the shaft. Thus, the supercharger compresses air and sends it to the engine as the compressor impeller rotates.

The turbocharger shaft is supported by, for example, a semi-floating bearing. The semi-floating bearing is an annular member. A bearing surface is formed on the inner peripheral surface of the semi-floating bearing. Patent Document 1 describes a supercharger on which a so-called multi-arc bearing is mounted. The bearing surface shape of the multi-arc bearing is a shape in which a plurality of arcs are connected in a cross section perpendicular to the shaft.

JP-A-1-193409

By the way, the viscosity of the lubricating oil that lubricates between the shaft and the bearing surface depends on the oil temperature. Therefore, if the amount of oil flowing into the gap between the shaft and the bearing surface (outflowing from the gap) becomes too large, the cooling effect of the oil film by the lubricating oil becomes too high. As the oil film temperature decreases, the viscosity of the lubricating oil does not decrease and the mechanical loss increases.

An object of the present disclosure is to provide a multi-arc bearing and a supercharger that can sufficiently raise the temperature of the lubricating oil and reduce mechanical loss.

In order to solve the above problems, a multi-arc bearing according to the present disclosure includes a bearing surface in which a cross-sectional shape perpendicular to the axial direction of the shaft is a shape including a plurality of arcs, and the bearing surface. An oil supply groove extending and having a bearing clearance at a front end portion in the rotational direction of the shaft that is smaller than a bearing clearance at a rear end portion in the rotational direction.

The oil supply groove is disposed between two arcs adjacent to each other in the rotation direction of the shaft, and the bearing surface has an enlarged portion in which the bearing clearance continuously increases in the rotation direction and a bearing clearance continuously decreases in the rotation direction. The reduction units may be alternately arranged in the rotation direction.

The front side end may be continuous with the reduced portion, and the rear side end may be continuous with the enlarged portion.

A semi-floating bearing having an annular main body having a bearing surface formed on the inner peripheral surface thereof may be used.

In order to solve the above problems, the turbocharger of the present disclosure includes the multi-arc bearing.

According to the present disclosure, it is possible to sufficiently raise the temperature of the lubricating oil and reduce mechanical loss.

It is a schematic sectional drawing of a supercharger. It is an extraction figure of the dashed-dotted line part of FIG. 3A is a diagram showing a cross section taken along the line III-III in FIG. 2, and FIG. 3B is a diagram showing an extracted broken line portion in FIG. 3A.

Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding, and the configuration is not limited unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a schematic sectional view of the supercharger C. In the following description, the arrow L direction shown in FIG. 1 will be described as the left side of the supercharger C, and the arrow R direction will be described as the right side of the supercharger C. As shown in FIG. 1, the supercharger C includes a supercharger main body 1. The supercharger main body 1 includes a bearing housing 2. A turbine housing 4 is connected to the left side of the bearing housing 2 by fastening bolts 3. A compressor housing 6 is connected to the right side of the bearing housing 2 by fastening bolts 5. The bearing housing 2, the turbine housing 4, and the compressor housing 6 are integrated.

The bearing housing 2 is formed with a bearing hole 2a that penetrates the supercharger C in the left-right direction. The bearing housing 2 is formed with an oil supply passage 7 for introducing lubricating oil from the outside into the bearing hole 2a. The bearing hole 2 a is filled with lubricating oil supplied from the oil supply passage 7. A semi-floating bearing S is accommodated in the bearing hole 2a. A shaft 8 is rotatably supported by the semi-floating bearing S. A turbine impeller 9 is integrally fixed to the left end portion of the shaft 8. The turbine impeller 9 is rotatably accommodated in the turbine housing 4. A compressor impeller 10 is integrally fixed to the right end portion of the shaft 8. The compressor impeller 10 is rotatably accommodated in the compressor housing 6.

The compressor housing 6 is formed with an intake port 11 that opens to the right side of the supercharger C. The intake port 11 is connected to an air cleaner (not shown). Further, in a state where the bearing housing 2 and the compressor housing 6 are connected by the fastening bolt 5, a diffuser flow path 12 that pressurizes air is formed by the facing surfaces of the bearing housing 2 and the compressor housing 6. The diffuser channel 12 is formed in an annular shape from the radially inner side to the outer side of the shaft 8. The diffuser flow path 12 communicates with the intake port 11 via the compressor impeller 10 on the radially inner side.

The compressor housing 6 is provided with an annular compressor scroll passage 13. The compressor scroll flow path 13 is located on the outer side in the radial direction of the shaft 8 than the diffuser flow path 12. The compressor scroll passage 13 communicates with an intake port of an engine (not shown). The compressor scroll channel 13 also communicates with the diffuser channel 12. Therefore, when the compressor impeller 10 rotates, air is taken into the compressor housing 6 from the intake port 11. Further, the sucked air is increased in pressure and pressure in the process of flowing between the blades of the compressor impeller 10. The air increased in speed and pressure is increased in pressure (recovered by pressure) in the diffuser flow path 12 and the compressor scroll flow path 13 and is guided to the engine.

A discharge port 14 is formed in the turbine housing 4. The discharge port 14 opens on the left side of the supercharger C. Further, the discharge port 14 is connected to an exhaust gas purification device (not shown). The turbine housing 4 is provided with a flow path 15 and an annular turbine scroll flow path 16. The turbine scroll passage 16 is located on the radially outer side of the shaft 8 with respect to the passage 15. The turbine scroll passage 16 communicates with a gas inlet (not shown). Exhaust gas discharged from the exhaust manifold of the engine is guided to the gas inlet. Further, the turbine scroll flow path 16 communicates with the flow path 15. Therefore, the exhaust gas guided from the gas inlet to the turbine scroll passage 16 is guided to the discharge port 14 via the passage 15 and the turbine impeller 9. The exhaust gas guided to the discharge port 14 rotates the turbine impeller 9 in the flow process. The rotational force of the turbine impeller 9 is transmitted to the compressor impeller 10 via the shaft 8. As described above, the air is pressurized and guided to the engine by the rotational force of the compressor impeller 10.

FIG. 2 is an extraction diagram of a one-dot chain line portion of FIG. As shown in FIG. 2, the semi-floating bearing S has an annular main body 20. The main body 20 is accommodated in the bearing hole 2a. Bearing surfaces 20 a are formed on the inner periphery of the main body 20 on the turbine housing 4 side and the compressor housing 6 side, respectively. The bearing surface 20 a on the turbine housing 4 side and the bearing surface 20 a on the compressor housing 6 side are separated from each other in the axial direction of the shaft 8.

Further, a pin hole 20b is formed between the two bearing surfaces 20a in the main body portion 20. The pin hole 20b penetrates the main body 20 in a direction intersecting with the axial direction of the shaft 8, in this case, in the radial direction of the shaft 8. On the other hand, the bearing housing 2 is formed with a through hole 2b. The regulation pin 21 is press-fitted and fixed in the through hole 2b. The through hole 2b is provided at a position facing the pin hole 20b. The restriction pin 21 fixed to the through hole 2b has its tip inserted into the pin hole 20b. Thereby, the semi-floating bearing S is restricted from moving in the rotational direction of the shaft 8.

A gap 23 is formed between the outer peripheral surface of the main body 20 and the inner peripheral surface of the bearing hole 2a. Damper surfaces 20 c are formed on the outer peripheral surface of the main body 20 at both axial ends of the shaft 8. The damper surface 20c is a portion where the gap 23 formed between the main body 20 and the bearing hole 2a is the smallest. By causing the lubricating oil supplied between the damper surface 20c and the inner peripheral surface of the bearing hole 2a to function as a damper, the vibration of the shaft 8 is suppressed.

The shaft 8 is provided with a flange portion 8a at a portion located in the bearing hole 2a. The flange portion 8a has an outer diameter larger than a portion inserted through the main body portion 20 of the semi-floating bearing S. The flange portion 8a faces the end surface of one of the main body portions 20 in the axial direction of the shaft 8 (here, the left side in FIG. 2). On the other hand, the oil draining member 22 is disposed opposite to the other end surface of the main body 20 in the axial direction of the shaft 8 (here, the right side in FIG. 2). The oil draining member 22 is fixed to the shaft 8. The oil draining member 22 scatters the lubricating oil from the semi-floating bearing S toward the compressor impeller 10 to the outside in the radial direction of the shaft 8. As a result, leakage of lubricating oil to the compressor impeller 10 side is suppressed.

Thus, the semi-floating bearing S is located between the flange portion 8a of the shaft 8 and the oil draining member 22. Further, both end surfaces of the main body portion 20 in the axial direction face the flange portion 8a and the oil draining member 22, respectively. Therefore, the semi-floating bearing S receives the radial load of the shaft 8 on the two bearing surfaces 20a. Further, the semi-floating bearing S receives a thrust load from the flange portion 8 a and the oil draining member 22.

The bearing housing 2 is formed with an oil supply passage 7 for guiding lubricating oil from the outside to the bearing hole 2a. The oil supply passage 7 is branched into two passages in the bearing housing 2. The oil supply passage 7 is open to the damper surface 20c on the turbine housing 4 side and the damper surface 20c on the compressor housing 6 side, respectively. The two openings 7a of the oil supply passage 7 are located radially outward of the bearing surface 20a.

Also, oil guide holes 20d are formed in the main body 20 at positions facing the two openings 7a, respectively. The oil guide hole 20d penetrates from the damper surface 20c to the bearing surface 20a. Three oil guide holes 20d are provided at equal intervals on the turbine housing 4 side and the compressor housing 6 side, respectively, spaced apart from each other in the circumferential direction of the main body 20 (FIGS. 3A and 3B). reference).

Therefore, on each of the turbine housing 4 side and the compressor housing 6 side, a part of the lubricating oil guided from the opening 7a to the bearing hole 2a is guided to the bearing surface 20a through the oil guide hole 20d. Thereby, sufficient lubrication oil can be ensured in both bearing surfaces 20a.

In the bearing surface 20a, an oil supply groove 20e is formed at a portion where the oil guide hole 20d is opened. Here, the oil supply groove 20 e extends from one end of the bearing surface 20 a to the other end in the axial direction of the shaft 8. Then, the lubricating oil is guided to the oil supply groove 20e from the oil guide hole 20d. The lubricating oil guided to the oil supply groove 20e spreads in the axial direction of the shaft 8 along the oil supply groove 20e.

3A is a diagram showing a cross section taken along line III-III in FIG. 2, and FIG. 3B is a diagram showing an extracted broken line portion in FIG. 3A. The bearing surface 20a on the turbine housing 4 side and the bearing surface 20a on the compressor housing 6 side have substantially the same shape. Therefore, in order to avoid duplication, the bearing surface 20a on the turbine housing 4 side will be described, and the description on the bearing surface 20a on the compressor housing 6 side will be omitted.

As shown in FIG. 3A, the bearing surface 20a has a shape in which a cross-sectional shape perpendicular to the axial direction of the shaft 8 (hereinafter simply referred to as a cross-sectional shape) includes a plurality of (here, three) arc lobes. It has become. Specifically, an oil supply groove 20e is formed on the bearing surface 20a. The oil supply groove 20e is formed between two circular arc lobes adjacent in the rotation direction of the shaft 8. In other words, the oil supply groove 20 e is formed across two arcs lobe adjacent to each other in the rotation direction of the shaft 8.

Also, the cross-sectional shape of the bearing surface 20a includes a plurality of circular arc lobes, whereas the cross-sectional shape of the shaft 8 is a circle. Therefore, when the shaft 8 is in a position coaxial with the main body portion 20, the bearing clearance (separation distance between the shaft 8 and the bearing surface 20 a) is not uniform in the circumferential direction of the shaft 8.

Specifically, the bearing surface 20a has an enlarged portion 20f and a reduced portion 20g. The enlarged portion 20f is a portion where the bearing clearance continuously increases (increases gradually) in the rotation direction of the shaft 8 (the direction indicated by the arrow in FIG. 3A). The reduction part 20g is a part where the bearing clearance is reduced (gradually reduced) continuously in the rotation direction. As shown in FIG. 3A, the enlarged portions 20f and the reduced portions 20g are alternately arranged in the rotation direction. And the front side edge part 20h ahead of the rotation direction of the shaft 8 among the oil supply grooves 20e continues to the reduction part 20g. Of the oil supply groove 20e, the rear side end 20i behind the rotation direction of the shaft 8 is continuous with the enlarged portion 20f.

Further, as shown in FIG. 3B, the bearing clearance cl ₁ (gap with the shaft 8) in the front end 20h in the rotational direction front of the shaft 8 in the oil supply groove 20e is the rear side in the rear in the rotational direction. It is smaller than the bearing clearance cl ₂ (gap with the shaft 8) at the end 20i.

Lubricating oil guided to the oil supply groove 20e is rotated along with the rotation of the shaft 8 as shown by the solid line arrow in FIG. The lubricating oil then flows into the gap (bearing clearance) between the front end 20h and the shaft 8. A part of the lubricating oil after lubricating the bearing surface 20a is discharged from the axial end of the bearing surface 20a (main body portion 20). As shown in FIG. 2, an oil drain hole 20 j is formed between the two bearing surfaces 20 a in the main body 20. The oil drain hole 20j penetrates in the direction intersecting the axial direction of the shaft 8, in this case, in the radial direction of the shaft 8. On the other hand, the bearing housing 2 is provided with a counter hole 2c at a position facing the oil drain hole 20j. Part of the lubricating oil after lubricating the bearing surface 20a is discharged from the bearing hole 2a through the oil drain hole 20j and the counter hole 2c.

At this time, the viscosity of the lubricating oil that lubricates between the shaft 8 and the bearing surface 20a depends on the oil temperature. Therefore, if the amount of oil flowing into the gap between the shaft 8 and the bearing surface 20a (outflowing from the gap) becomes too large, the temperature of the lubricating oil is not sufficiently raised by heat from peripheral members such as the shaft 8. For this reason, the mechanical loss increases without the viscosity of the lubricating oil decreasing. Here, the bearing clearance cl ₁ of the front end portion 20h is formed smaller than the bearing clearance cl ₂ of the rear-side end portion 20i. Therefore, as compared with the case where larger than the bearing clearance cl ₂ of the bearing clearance cl ₁ of the front end portion 20h rear end portion 20i, the oil amount of the lubricating oil flowing into the gap between the shaft 8 and the bearing surface 20a is It can be suppressed. As a result, the lubricating oil can be sufficiently heated to reduce mechanical loss.

It is also conceivable to reduce the mechanical loss by adjusting the oil amount by hydraulic control or the like. However, in this case, control according to the rotational speed of the shaft 8 is required. Further, depending on the control process, there is a possibility that the lubricating oil becomes insufficient. On the other hand, when the bearing clearance cl ₁ of the front side end 20h is formed smaller than the bearing clearance cl ₂ of the rear side end 20i, the minimum required oil amount can be simply and reliably without complicated control processing. Can be supplied.

In the above-described embodiment, the case where the oil supply groove 20e extends from one end of the bearing surface 20a to the other end in the axial direction of the shaft 8 has been described. The oil supply groove 20e does not need to extend from one end of the bearing surface 20a to the other end as long as it extends in the axial direction of the shaft 8. However, if the oil supply groove 20e extends from one end to the other end of the bearing surface 20a, an effect of suppressing the amount of lubricating oil flowing in can be expected over the entire length in the axial direction. Therefore, the effect of reducing mechanical loss is great.

In the above-described embodiment, the oil supply groove 20e is disposed between the arcs lobe adjacent to each other in the rotation direction of the shaft 8. In the bearing surface 20a, the case where the enlarged portions 20f and the reduced portions 20g are alternately arranged in the rotation direction has been described. The oil supply groove 20e may not be provided between the adjacent arc lobes. Further, in the bearing surface 20a, the enlarged portions 20f and the reduced portions 20g may not be alternately arranged in the rotation direction. In this case, there is a possibility that a boundary portion where adjacent arcs are continuous remains and a step is formed in the boundary portion. This level difference disturbs the flow of the lubricating oil. On the other hand, the oil supply groove 20e is disposed between the adjacent arc lobes, and the enlarged portions 20f and the reduced portions 20g are alternately arranged in the rotation direction on the bearing surface 20a. Play. That is, in the process of forming the oil supply groove 20e, the boundary portion between the adjacent arc lobes is removed. For this reason, it is possible to avoid a situation in which a step remains at the boundary portion and disturbs the flow of the lubricating oil.

In the above-described embodiment, the case where the front side end portion 20h is continuous with the reduced portion 20g and the rear side end portion 20i is continuous with the enlarged portion 20f has been described. The oil supply groove 20e may not be disposed between the adjacent arc lobes. The front side end portion 20h may not be continuous with the reduced portion 20g. The rear end 20i may not be continuous with the enlarged portion 20f. For example, the oil supply groove 20e may be formed in the reduced portion 20g in each arc lobe, not between the adjacent arc lobes. However, the front side end portion 20h is continuous with the reduced portion 20g, and the rear side end portion 20i is continuous with the enlarged portion 20f, thereby providing the following effects. That is, it is possible to secure a large area of the reduced portion 20g where the oil film pressure is generated, and to improve the bearing performance.

In the above-described embodiment, the case where the multi-arc bearing is the semi-floating bearing S has been described. The multi-arc bearing may be, for example, a full floating metal that is not restricted in movement in the rotation direction and rotates with the rotation of the shaft 8. Here, in general, the semi-floating bearing has a larger mechanical loss than the full floating metal. Therefore, when the multi-arc bearing is the semi-floating bearing S, the mechanical loss reduction effect is further increased.

Further, in the above-described embodiment, a case has been described in which three oil supply grooves 20e are provided, one in each of the three arc lobes. For example, the oil supply groove 20e may be provided only at one or two of the three portions between the three arcs. In this case, the inflow of the lubricating oil to the bearing surface 20a is further suppressed. Therefore, it is possible to further reduce mechanical loss.

In the above-described embodiment, the semi-floating bearing S in which the bearing surface 20a including the three arc lobes in the cross-sectional shape is described as an example. Note that the number of arcs lobes may be two, or four or more.

The preferred embodiments have been described above with reference to the accompanying drawings, but it goes without saying that each configuration is not limited to the above embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope.

The present disclosure can be used for a multi-arc bearing and a supercharger that support a shaft.

lobe Arc C Supercharger S Semi-floating bearing 20 Main body 20a Bearing surface 20e Oiling groove 20f Enlarged portion 20g Reduced portion 20h Front end 20i Rear end

Claims (7)

A bearing surface in which a cross-sectional shape perpendicular to the axial direction of the shaft includes a plurality of arcs;
An oil supply groove that is provided on the bearing surface, extends in the axial direction of the shaft, and has a bearing clearance at a front end in a rotational direction of the shaft that is smaller than a bearing clearance at a rear end in the rotational direction;
Multi-arc bearings with The oil supply groove is disposed between two arcs adjacent to each other in the rotation direction of the shaft,
The bearing surface is
An enlarged portion in which the bearing clearance continuously extends in the rotation direction;
A reduced portion in which the bearing clearance is continuously reduced in the rotational direction;
The multi-arc bearing according to claim 1, wherein are arranged alternately in the rotation direction. The front end is continuous with the reduced portion;
The multi-circular bearing according to claim 2, wherein the rear side end portion is continuous with the enlarged portion. The multi-arc bearing according to claim 1, wherein the multi-circular bearing is a semi-floating bearing having an annular main body having the bearing surface formed on an inner peripheral surface. The multi-arc bearing according to claim 2, which is a semi-floating bearing having an annular main body portion having the bearing surface formed on an inner peripheral surface. The multi-arc bearing according to claim 3, which is a semi-floating bearing having an annular main body portion having the bearing surface formed on an inner peripheral surface. A supercharger comprising the multi-arc bearing according to any one of claims 1 to 6.

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